Production of diolefines



Patented Aug. 22, 1933 UNITED STATES PATENT raoooo'rrou or more No Drawing. Application J1me r2. rose, Serial No. 461.8%, and in Germany duty 22. 1920 6 Claims.

This invention relates to improvements in the manufacture and production of diolefines.

We have found that butadiene or the other corresponding diolefines are obtained in an advantageous manner from 1.3-buty1ene glycol or other l.3- dihydroxy compounds such as 2-methyl-l.3-. butylene glycol or 2.3-dimethyl-2.3-butanediol by leading the dihydroxy compounds over catalysts which favor the splitting off of water at elevated 10 pressures preferably of from about 2 to 20 at-- mospheres, preferably at a pressure of about 10 atmospheres, and at elevated temperatures of from about 250 to 400 centigrade, preferablyat temperatures of from about 270 to 300 centigrade. As the catalysts may be mentioned for example phosphoric acid, red phosphorus, sodium phosphate, potash alum, aluminium oxide activated with a little copper sulphate, aluminium phosphate, thorium oxide and the like, or min tures of these, if desired precipitated onto car riers. The employment of the said elevated pressure has the great advantage that a greatly increased throughput was obtained, surprisingly without any substantial decrease in percentage yield, thatis to say a much larger amount of diolefines is obtained for a given reaction space. Too high pressures may, however, cause a decrease in yield.

lhe following examples will further illustrate 3 the nature of this invention, but the invention is not restricted to these examples.

Example 1 The mixture described in Example 1 is led under the conditions therein specified over a catalyst of silica gel which has been impregnated with monosodium phosphate and a very small amount of phosphoric acid.v The ratio or the throughput thus obtained to the throughput at ordinary pressures is 5:13.. The yield'of crude butadiene, similarly to that obtainable at ordi-.

5 nary pressure, is from about 65 to 70 per cent.

which comprises passing a 1.3-butylene glycol at a pressure of about 10 to 20 atmospheres and (or. w ll-fill? Example 3 'lhe mixture described in Example 1 is led under the conditions therein specified over I a catalyst prepared by impregnating granular m pumice stone with phosphoric acid. The ratio of the throughput thus obtainable to the throughput at ordinary pressure is 5:2. The yield of crude butadiene obtained is, as at ordinary pres sure, from about to per cent.

- Example 4 A mixture of 2methyl-l.3-butylene glycol and water vapor is passed over the catalyst described in Example 2, under the same conditions as those described in Example 1. The throughput per unit of space in the reaction vessel and per unit oi time is twice that, which is attained under atmospheric pressure, and the percentage yield is the same, namely about to to 65' per cent.

What we claim iStl. A process for the production oi a dioleiine, which comprises passing a lB-butylene glycol at a pressure. of about 2 to 20 atmospheres and at a temperature of about 250 to too" centigrade over a dehydration catalyst.

2. A process for the production of a diolefine. which comprises passing a 1.3-butylene glycol at a pressure of about? to so atmospheres and at a temperature oi about 2510 to 300 C. over a dehydration catalyst.

3. A process tor the production of a diolefine,

which comprises passing a 1.3-butylene glycol with added water vapor at a pressure of about 2 to 20 atmospheres and at a temperature of about 250.to 400 C. over a dehydration catalyst. a. A process for the production of butadiene, which comprises passing 1.3-buty1ene glycol in admixture with the same amount of water vapor at a temperature oi about 300 centigrade and at a pressure of about 10 atmospheres over a catalyst prepared by dehydration of monosodium phosphate.

5. A process for the production of a diolefine, which comprises passing a 1.3-buty1ene glycol at a pressure of about 10 to 20 atmospheres and at a temperature of about 250 to 400 C. over 2. dehydration catalyst.

6. A process forythe production of ,a dloleflne,

at a temperature of about 270? to 300 C. over a dehydration catalyst.

MAR'I'IN,MUEI.LER-CUNRADI.

ERNST OIBER. 

